Deformational behaviours of alluvial units detected by advanced radar interferometry in the vega media of the segura river, southeast spain

Carmelo Conesa‐garcía, Roberto Tomás, Gerardo Herrera, Francisco López‐bermúdez, Miguel Cano, Francisca Navarro‐hervás, Pedro Pérez‐cutillas
2016 Geografiska Annaler  
14 It is widely known that differential land subsidence in a valley significantly controls its fluvial dynamics. 15 Nevertheless, major uncertainty exists about the way in which alluvial forms respond to this process. Alluvial 16 sediments constitute loose and unconsolidated deposits characterized by their low strength and bearing capacity. 17 These sedimentary units have a moderate to very high compressibility, which depend mainly on the physical 18 properties of the sediments and depositional
more » ... ts and depositional environments. In this study, morphological and lithostratigraphic 19 data have been combined with Advanced Differential Interferometry (A-DInSAR) to detect changes in alluvial 20 landform elevations and to verify the existence of a differential subsidence pattern influenced by active 21 sedimentary dynamics. For this purpose, the middle reach of the Segura River valley (Vega Media of the Segura 22 River, VMSR), in south-east Spain, was chosen as the study area. The VMSR is an alluvial area affected by 23 subsidence processes in close conjunction with depositional conditions, ground-water withdrawals and faults. A 24 high scale mapping of the main younger sedimentary units was carried out by combining multi-temporal aerial 25 photographs, high resolution DEMs derived from LIDAR data, GNSS data and field work. In addition, 26 lithostratigraphic descriptions were obtained from geotechnical drilling and trenching. Finally, ground surface 27 displacements, measured using A-DInSAR for the periods 1995-2005 and 2004-2008, allowed the determination 28 of elevation rates and ground deformation associated with the different alluvial units. The results from this 29 analysis revealed four typical deformational behaviours: a) Non-deformational units (cemented alluvial fans and 30 upper fluvial terraces); b) Slightly deformable units (lower terraces and old abandoned meanders); c) Moderately 31 deformable units (lateral accretion zones and abandoned meanders before channelisation in 1981); and d) highly 32 deformable areas (recently active meanders associated with artificial cutoffs by channelisation, non-active 33 floodplains and spilling zones). 34 35
doi:10.1111/geoa.12121 fatcat:ugmnocr4djecfisnhhgvud2gta